1. Field of the Invention
The present invention is suited for utilization in the medical field, and is related to a system and a method for assisting image diagnosis using three dimensional image data. The present invention is also related to a computer readable recording medium having a diagnosis assisting computer program stored thereon.
2. Description of the Related Art
In image diagnosis, there are cases in which images of a subject obtained during recent examinations (hereinafter, referred to as “current images”) are compared against images of the same subject obtained in previous examinations (hereinafter, referred to as “past images”), to confirm changes in symptoms of disease (hereinafter, referred to as “comparative image observation”). A technique that generates and displays an image that represents the differences between a current image and a past image (temporal subtraction technique) is known as a technique for assisting comparative image observation. For example, U.S. Pat. No. 7,620,229 discloses an apparatus that generates and displays a subtraction image from projection images generated from three dimensional images.
In many cases, comparative image observation is performed with respect to two images. However, there are cases in which images obtained from two or more prior examinations are compared in order to confirm the progress of treatment and to consider treatment protocols. That is, there are cases in which it becomes necessary to understand stepwise changes that occur among three or more images. However, subtraction images cannot represent stepwise changes that occur among three or images in an easily understandable format.